Springs and Circuits
by Rainne
Summary: Crossover. Kaylee makes a very special new friend in a scrap yard, and learns something surprising about how she came to be on Serenity.


Disclaimer: Dr. Who and Firefly- two things I would very much like to own, two things that I very much do not own.

Author's Notes: Study for finals, write fanfic, study for finals, write fanfic... Heh, as if there's a choice. Here you go, a combination of two of my obsessions, one old and another new. Set sometime pre-Big Damn Movie and pre-first season but still with the Ninth Doctor. I hope you enjoy reading it half as much as I enjoyed writing it. Please review!

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Kaylee was happy. Not an unusual state, to be sure, but some days... She thought back on her father's face as she had untangled herself from his fierce hug the day she had left. She would never forget how all of that pent-up fear had tightened every muscle in his face. Serenity was nothing like home, at least not on the surface. But Kaylee liked to think, most days was sure, that under the surface Serenity was more of a home to her than any place would ever be. That being said, Kaylee was so glad to be off the ship for a few days' leave she was practically dancing through the scrap yard. Jobs had been even scarcer than usual lately (nobody was mentioning the fact that they didn't have the fuel to get to the next planet- hence the leave) and the young mechanic could feel the tension building as easily as she could a failing throttle barrel spring in her beloved ship's engine.

Speaking of which... "Ooh!" Kaylee lunged for a rusty bit of metal sticking out of a pile of other rusty bits of metal. "_Liú_," she breathed as she turned the part over in her hands, examining it from every angle. Kaylee slowly emerged from her haze of shopper's delight as she became aware of a very angry voice drifting over the scrap heaps. The voice was swearing creatively, Kaylee could tell that just as easily as she could tell it was male, although she'd never heard the language being shouted before.

Curiosity amplifying her concern, Kaylee tracked the voice deeper into the yard. Rounding one heap, she came across a strange sight indeed. A tall man with close-cropped brown hair wearing a black leather jacket and black pants was raging at a large blue box that sat among the piles. Kaylee had never seen anything quite like the blue box before, but she noticed that it had doors and windows, a blue light on top, and the words POLICE PUBLIC CALL BOX printed in white on black above the doors. Kaylee winced as the man kicked the box hard once, twice, before he turned away to clutch his now injured foot. "You okay?" she called to him.

The man spun around to stare at her, seeming almost gape-mouthed in shock at her existence, "Am I-? Yes, fine- I'm fine." As the man turned away to glare at the box, Kaylee cautiously stepped a bit closer.

"What's that thing? If you don't mind me asking," she said, poking a thumb at the box as she approached.

The man glared at the box, "That thing... that _thing_... is a piece of rubbish, that's what that thing is. That's all, rubbish, nothing to worry yourself with."

Once she was close enough, Kaylee reached out a tentative hand towards the box. Her eyes told her it was wooden, she noticed a spot where the paint was chipping off. Her fingers, however, were more interested in the humming going on within it. The whole thing was just... vibrating a little, very much like her own Serenity. Kaylee put both her hands on the box, her eyes drifting shut on their own, and the humming became her entire world. And there was something wrong in that world. "What is this thing?" she asked again, eyes still shut and hands ever so slowly moving across the surface of the box. When the man didn't answer, she stepped back, breaking off contact, with a frown. Kaylee saw that the man was staring at her with naked curiosity; she would have blushed if she wasn't so distracted. "Is this a spaceship?" She wasn't sure where the question had come from, but at least it made the man both close his mouth and blink.

"Got it in one, miss. How'd you know?"

"It's Kaylee. Kaylee Frye. And I just... knew. See- it's hummin', just like Serenity."

Apparently the man's face had yet more variations on the theme of surprised to show her. This one was more about the eyebrows and their ability to jump nearly to his hairline. "Serenity? You mean, Firefly-class cargo ship Serenity?" The last was less of a question and more of a statement, as if he had no doubt that he was right.

Kaylee beamed, "You've heard of us? Well ain't that shiny! Hey, if you got anything needs hauling, or maybe you need passage somewhere, you oughta talk to our cap'n 'cause we could use the coin about now, then maybe I could just _buy_ parts 'stead of scroungin' 'round old scrap heaps. Not that I got anything against scrap heaps, mind, I know I've found some of the best parts ever in places like this. In fact, I'd say most of Serenity's engine right now came out of somebody's garbage, and there ain't no better ship in the 'verse, that's for sure."

The man was smiling now, a crooked thing that Kaylee liked, it made her want to smile back, so she did. "That's a fantastic offer, Kaylee Frye," he said in a kindly tone that matched his smile perfectly, "But I haven't got anything to haul, and... I don't doubt you have your hands full with passengers."

Kaylee blinked at this, but pressed the sale, as the captain had taught her, "There's plenty of room aboard Serenity. And, begging your pardon, but it doesn't look to me like your ship's going anywhere in a hurry. I'd have to take a look to see what's really going on, but I'd say you got a short somewhere, it's throwing everything off. And I know real well how tough electrical problems are to suss out, so how's about we give you a lift somewhere's you can get it fixed?" She put on her best and brightest smile, with maybe the slightest hint of flirtation, just for good measure.

The man chuckled, very low and gentle, looking down at the ground a moment before meeting her eyes again. "Kaylee Frye," he said, his voice sounding awed, of all things, "You think you know what's wrong with my ship?"

Kaylee suddenly felt a little uneasy. There was something in his gaze- like he was looking at her but not seeing her, or maybe not seeing the her that was looking at him... She shrugged, "I don't know. I ain't ever seen a ship like this, I wouldn't know where to start- I mean, where's the engine?" She peered at the box, now genuinely wondering exactly how it was a spaceship.

"You want to see?" the man said and stalked over to the door. He held it open for her, saying, "Go on, take a look, Kaylee Frye. What harm could it do?"

Curiosity now rather at odds with her better judgment, Kaylee edged her way past the man and through the door. Once inside the box, a surprised look of her own swept over her face. "_Wo de ma!_" she gasped, gazing around the space, "_Géng dá shang lî!_"

"That it is," the man replied, pride evident in his voice. He had entered after her, and proceeded to take in the view of the mechanic wandering around the wide, circular expanse in astonishment.

It didn't last too long, however, since after less than a minute she turned back to him, frowning again. "Are you Alliance?"

The man burst out laughing, "Alliance? Why in the worlds would you think a thing like that?"

Kaylee shifted uncomfortably, crossing her arms. She didn't like the way the man was looking at her now, like she was so... simple. "Because I ain't ever seen anything like this, and I've been lots of places. Only place that might have something like this would be in the Core, and the Core's Alliance."

"All right, that's logical, I'll give you that one," the man conceded, "You're a sharp one, Kaylee. But you're also wrong. 'M not Alliance."

"Well, what are you- who are you?" The sound of the short somewhere in his ship's system was starting to irritate Kaylee, like a sour note in a symphony.

"Me? I'm the Doctor."

"You're a doctor?"

"Not a doctor, love, _the_ Doctor."

Kaylee was getting more puzzled by the minute, "Okay. And your... ship. What's her name?"

The Doctor's prideful smile returned as he stepped up to what must have been the ship's consol, which he patted tenderly, "This is the TARDIS."

"She don't have a name?"

"Don't need one, really. The last of her kind, she is. Don't make 'em like this anymore... not for a very long time." Kaylee found herself blinking back tears almost before she had noticed the bone-deep sorrow in the Doctor's reply. A silence that echoed off of the far walls stretched between them. Eventually, the Doctor seemed to recall her presence, "So, Kaylee Frye, you mentioned something 'bout a short?"

"Yeah, um, you can't hear that?" Once the sadness had passed, the dissonance within the ship's hum was back full-force, almost a physical grating on Kaylee's nerves.

The Doctor looked slightly offended at the question, "Well, now, I've been with the TARDIS for a right long time. Can't listen to every solitary sound that whole while- I'm liable to go bonkers. But a fresh pair of ears," he gestured towards her, "Now I think that might be just the ticket. So, go on, poke around a bit, see if you can't get us off this rock. Honestly, the 26th century, sixth human empire not ten years from collapse? Not where I'd like to hang my hat for the rest of my days, if you don't mind me saying."

Had the short not commanded her attention Kaylee might have noticed the oddness of the Doctor's remark, but, having been given permission, she was already on the trail. She started up at the consol, circling around the phosphorescent green tube protruding from the center that she assumed was some power source going by the increased intensity of the vibration felt when she placed her hands on the consol. "Nope, not up here," she murmured mostly to herself. The Doctor didn't respond, in any case, preferring to stand with his arms crossed and observe the mechanic intently. Kaylee stepped off of the consol's platform and started to slowly make her way around the room, her eyes half closed and her arms stretched out so her hands could touch the vaguely organic-looking columns and perhaps even the air itself. "What was going on when she stopped working, Doctor?" she asked.

The Doctor blinked when he realized she was speaking to him, "Oh, when she stopped? Well, I was just trying to get her started again and she wouldn't- uh... dematerialize. She wouldn't dematerialize for me, Kaylee." His voice sounded so terribly ill at ease that Kaylee stopped and looked at him. His eyes were on her, and she could tell he was waiting for her reaction.

"Your ship dematerializes, or would if she could. Okay," she said, with a little nod and smile. He grinned back at her, practically ear-to-ear. Kaylee felt a little ball of warmth settle into her stomach upon seeing that grin, it was so- heartening. She caught herself basking in it when the Doctor made a small gesture with his hand for her to continue. Back on task, Kaylee kept moving around the perimeter of the room, listening and touching just as she would in Serenity's engine room. Suddenly, just two feet shy of the door, she stopped. Crouching down, she placed both of her palms flat on the grate that served as a floor. "Ohh yeah," she said, "That's it. Something is not right down there, I'd bet Serenity on it."

The Doctor jogged over to her, excitement at odds with worry on his face. He crouched as well and did some listening of his own, with his ear pressed against the grate, "I can hear it! How did I miss that?" He looked up at Kaylee, "This is a bit embarrassing, I must admit. That's the Dematerialization Circuit down there. Thought I'd checked it... Maybe I am going mad."

"We gotta get this grate up," Kaylee replied gently, feeling the Doctor's discomfort, and the pair set about the undertaking. Once that was finished, they poked their heads down into the jungle of TARDIS parts below.

"There, you see that?" the Doctor pointed his nose at something mostly hidden in the shadows.

"What, that?" Kaylee squinted into the darkness until the shape of the circuit became clear. She could just make out a silvery, blobby object with four knobs protruding from it. Attached to the knobs were four green disks that were in turn attached to four black disks. Wires grouped in bunches of three connected each disk to the others.

"See, now, I did check it, I know I did," the Doctor said, sounding frustrated, "And it's just fine... isn't it?"

"Nope. Sorry, Doctor. There's a wire loose, just there." Kaylee pointed towards a little wire dangling from the top black disk, almost hidden in the back of the circuit.

"You've got to be kidding me," the Doctor griped, but pulled out a small silver instrument from his pocket. He reached out and snatched up the wire, plugging it back into the disk it had come loose from and shining blue light on it that apparently came from the instrument.

Kaylee immediately sighed in relief as the sour note disappeared, her head falling against the Doctor's shoulder. "Ahh," she breathed, "That's so much better."

The Doctor shot an amused grin at her once they were again top-side of the grate, "It was that strong for you, eh? And you'd never even stepped inside a TARDIS before in your life. You're a remarkable girl, Kaylee Frye. Quite possibly the best mechanic in several centuries' time."

Kaylee was fully available for blushing this time, "Aw, you're real sweet, Doctor. I'm glad to help. Really glad, actually. I love Serenity, ain't no question about that at all, but sometimes I miss gettin' to work on different ships, like I did when I was in my daddy's shop. And this- well, this is 'bout as different as different can get."

The two shared a laugh before the Doctor said, "All right, then, let's talk about payment."

"_Fú kuân_? I don't need anything from you, Doctor, I just worked on a ship that dematerializes and's bigger on the inside than on the outside!"

"Really? You want nothing at all, not a thing? How about a trip through time, Kaylee Frye?"

"What? I don't understand." Kaylee's brow wrinkled as she watched the Doctor bound over to the consol.

"Come now," he said, "If you won't take payment, call it a test drive. Like to test out your handiwork, don't you?" He was already flipping switches, yanking levers, twisting knobs, and talking all the while, "We'll head to the past, I think. There's something to be said for surprise, considering the way your lot's heading. So the question is when? When would you like to go, Kaylee? Oh, quote me a where as well, if it's different from now."

Kaylee's mind raced as she listened to the various harmonies of the TARDIS's engines roaring into life, "I- I don't, um... How about... Eighth of August, 2516? Uh, on Athens?"

"Fantastic! I can't wait to see what happened." The Doctor inputted the information, and Kaylee was nearly knocked off her feet when the TARDIS lurched into motion. "Sorry about that," the Doctor called over to her, "It's better when you're up here, you get something to hold on to." The young mechanic staggered up to the consol and gripped it tightly, shooting an unseen grimace at the Doctor, who was beaming at everything delightedly, "You're the best of the lot, Kaylee Frye! I'm sure of it. Listen to her go, my dear TARDIS." The Doctor bent over and kissed the consol with quite a bit of passion just before the lurching ceased. He straightened with yet another grin, "Ah, and here we are. Outside that door, Miss Frye, is Athens, August eight, 2516." Kaylee looked to the door, uncertainty scrawled across her features. "Well, go on, then. Didn't come all the way here so you could stay inside and not take a look."

The Doctor came around the consol and scooped up Kaylee's hand, guiding her over to the door, which he opened about five inches before Kaylee pushed it shut. The Doctor's quizzical look met Kaylee's saucer-eyed one. "That's Athens out there!" she cried, voice as high-pitched as her eyes were round.

"Yeah, I know, I took us here. What's the issue, Kaylee? You act like you're surprised we're here. You knew this was a spaceship, knew it faster than most. I know I sprung the time-travel on you a bit, that was unfair, but there's no need to be squeamish." He was giving her that look again, the one that made her feel like a bug on his sleeve. When he opened the door again, Kaylee slipped outside as soon as the space was wide enough.

The sun beamed down over the planet's surface. A gentle breeze stirred the grass and the leaves. If she squinted, Kaylee could make out a crescent of Whitefall waxing in the south. She inhaled deeply and sure enough picked up two scents of home on the wind: crape jasmine and exhaust fumes. Gradually she noticed the Doctor standing behind her. When she turned to look, she found him glancing around the area, scratching the back of his head. "Nice planet," he remarked, "Very- pastoral." Kaylee wrapped her arms tightly around his waist and didn't let go until his own draped over her back. This time she felt his quiet laughter rumble up from inside his chest, along with a strange cadence of thumps...

The Doctor gently eased himself out of Kaylee's hug, and she beamed up at him. "Well, Miss Kaylee, here we are. August the eighth, 2516. Planet Athens. Was this a random date and place you chose, or not?"

"It's not random, Doctor, not by a long shot. This is the day Cap'n invited me to be Serenity's mechanic."

"Oh, is it? Well, an interesting choice, indeed. And I suppose you'd like to observe this momentous occasion?" Kaylee nodded eagerly, "Very well, then, lead on."

Twenty minutes' walking brought them into the tiny town Kaylee had once called home. The Doctor had briefed her on the way about the inadvisability of interfering with what they saw. "It's quite a lovely day here, Kaylee," he had said, "We wouldn't want to ruin it with paradoxes, now, would we? Just keep your head down and enjoy the show."

Kaylee's hometown had sprung up with the construction of a docking station for whatever ships stumbled upon Athens on their tour of the black. A market led off from the landing pad, which was little more than a giant square of pavement on the flattest bit of land. Kaylee and the Doctor approached the pad, on which a handful of ships were parked. When they were close, Kaylee suddenly let out a shriek that had the Doctor wincing and wiggling a finger in his ear. "Blimey, that wasn't half loud!" he cried, "What was that all about?"

Kaylee snatched the Doctor's arm and pointed at a tiny rust bucket of a ship on the pad, "Look! Look, Doctor! It's Serenity! Oh, ain't she beautiful! My beautiful girl!"

The Doctor squinted, "What, that? That's Serenity? Whew, and I thought the TARDIS was rough round the edges. You actually go into outer space in that, where there's no air to breathe or ground to catch you when it falls to pieces? OW!" Kaylee stalked off, not bothering to wait for the limping Doctor, at least for a few yards.

The pair got within twenty feet of the ship before the Doctor stopped Kaylee with a hand on her shoulder. He pointed to the recumbent figure of a young man sleeping on a rickety folding chair next to Serenity's lowered gangway. When Kaylee spotted him, she turned away with a hand covering her smiling face.

"Friend of yours?" the Doctor inquired.

"That's Bester, prob'ly the best mistake I ever made." Without further explanation, Kaylee padded a bit closer to Serenity and the dozing Bester. Despite the Doctor's urging her to stay out of sight, she got quite close to the ship's previous mechanic, close enough to enjoy the view of his sculpted torso. _Might've been a _go se_ mechanic, but he wasn't good for nothing,_ Kaylee mused nostalgically. She glanced up at the market which Serenity's open cargo bay faced, and wondered idly what Mal and Zoë were up to at this moment- this moment once gone, revived again by the accident of her meeting the Doctor. Her sudden burst of amazement at this extraordinary situation almost, but not quite, distracted her when she spotted herself cruising the market not ten yards away. She froze, able to do nothing but watch in shock.

The Doctor peered over to see what had so affected Kaylee and, realizing that it was Kaylee that had so affected Kaylee, sighed, "Oh, terrific. That's just- fantastic."

The mechanic had unfrozen some now, enough to notice that something that was supposed to be happening wasn't. She kept glancing down at the somnolent young man, then back at her strolling self some distance away, "Why isn't-? Bester, why aren't you-? Bester, wake up!"

The Doctor had to force himself not to physically restrain the mechanic from making more noise. "Kaylee," he whispered as loudly as he dared, "Remember what I said about paradoxes and how they can ruin your day?"

"But no, Doctor, this isn't right," she replied agitatedly, practically trembling as she bit her lower lip.

Just before the Kaylee in the marketplace walked out of sight, the Kaylee next to Bester released a wolf whistle that rang out across the countryside. With one mind she and the Doctor dived beneath the gangway just as Bester jerked up in his chair and the marketplace Kaylee looked in Serenity's direction. The pair didn't speak, didn't move, barely dared to breathe until a brief, giggly conversation passed on the other side of the gangway and two pairs of footsteps traveled over their heads and into the cargo bay. Afterwards, Kaylee was shocked to find that she was laughing, and kept laughing when she spotted the Doctor's severe glower. She was still laughing too hard to hear when the Doctor muttered in a tone bordering on disgust, "Humans."

Kaylee, sensing that she had fallen from the Doctor's good graces for the time being, stayed quiet on the walk back to the TARDIS. Or at least tried to stay quiet, for about half of the walk. Maybe a quarter. "Oh, come on, Doctor. That's how it happened! I remember- I remember the whistle, then I walked over, then we- well, then I met Mal and I became the mechanic. No harm done, it didn't set off no paradoxes, whatever that means. Look, I'm sorry if you're upset, but I think I just saved my future!"

"I think I agree with you, Kaylee."

"Oh, good. I thought you might be mad, since you told me not to interfere an' all."

The Doctor sighed, "It's just... Do y'ever feel like you can't go anywhere without something happening? Can't just visit somewhere nice and then leave, there's always some crisis to be averted, big or small?"

"Seems like it can't ever just go smooth?"

"Yes, that's the one. Why can't it ever just go smooth?"

"Don't know. You should talk to the cap'n, though, he asks that all the time."

"Maybe I will. Who can say?" Kaylee and the Doctor walked the rest of the way to the TARDIS hand in hand, the silence now much more comfortable, if a touch melancholy.

"So, what was the date before we left?" the Doctor asked, once again stationed at the consol.

Kaylee pondered the question from her seat nearby, "Hmm... The twenty-fourth, I think? Of March?"

"Yeah, sounds right." An intricate dance of switch-flipping, lever-pulling, knob-turning, and a lurch later, the TARDIS stilled once again. The Doctor smiled, "Running like a charm now. You're a wonder, Kaylee, the best there is."

"Aw, no more of that," she replied, "Weren't nothing you wouldn't've figured out soon enough."

"Maybe so, but maybe not. Luckily, I won't have to find out, thanks to you." The Doctor walked her over to the door, "It was lovely to meet you, Miss Kaylee Frye. Good luck in all things. I know once something else gives out round here, I'll think of you."

"G'bye, Doctor, you come visit if you're around here again." Kaylee placed her hands on his chest and stretched up on her toes to kiss his cheek.

The Doctor opened the door with a gallant bow, allowing Kaylee to step down from the TARDIS and back into the scrap yard. "Stand clear, now, Kaylee" were his last words to her before the engines began to roar once again and the TARDIS vanished into the air. Kaylee heaved a happy sigh, checked her pocket for the replacement throttle barrel spring, and made her way out of the yard.

"KAYLEE!" a voice nearly scared her out of her wits as she stepped into the street after paying for the part. She whipped around to find Mal barreling down on her. Serenity's captain swept her up into one of the tightest hugs of her entire life.

With her feet dangling off the ground and her lungs struggling for air, Kaylee whispered, "Hi."

Mal set her back down, cupping her face in his hands as he yelled, "Where in the gorram hell have you been?!"

"The scrap yard, cap'n, just like you told me to. Look!" she held up the spring, "I found a _wán béi_ replacement for that part I was tellin' you about last night? You know, the one that'll be the death of us all if it don't get replaced? You remember?"

Mal's face was a mask of stress and fear and pain, "Kaylee, that was a week ago. We ain't seen hide nor hair of you for a whole week. Now you tell me, right now, where have you been?"

Kaylee winced at Mal's distress and patted the side of his face in what she hoped was a soothing manner, "Aw, cap'n, I'm sorry. I had no idea I'd be gone so long. I been... I been savin' the future, cap'n. Or the present, I guess. It's all a little confusing, that's for sure. I met this man, the Doctor. You'd like him, cap'n, he's just like you."

Mal let out a sound somewhere between a moan and a sigh, and again wrapped Kaylee up in his arms, "_Meimei_, I don't got the foggiest idea what you're talkin' about, but I sure am glad you're back."

"Me, too, cap'n."

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Liú- lovely  
Wo de ma- Mother of God  
Géng dá shang lî- bigger on inside (approximately)  
Fú kuân- payment  
Go se- crap  
Wán béi- perfect  
Meimei- little sister

A/N: Wow, really high hug quotient for this fic. I shouldn't be surprised; I've got not only Kaylee in here, but also the Doctor- two folks who are born huggers if there ever were any. Man, the Doctor cannot be trusted around women of a certain age for any period of time. They fall in love with him every time, just like that! Moving on, does anybody know what Kaylee's homeworld is? You know, they say Mal's the big mystery on the show, but how much do we really know about little Kaylee? I picked Athens, the planet Whitefall orbits; it seemed to fit, it's a border world but not too small. Thanks goes out to the makers of the excellent Firefly wikipedia article that has listed every moon and planet mentioned in the show. More thanks goes out to the fine and sexy übernerds at the Whoniverse website. My God, I had no idea there was actual _logic_ involved in TARDIS technology. Anyway, enough with the rambling, thanks for reading!


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